Photocoagulator

Abstract

A photocoagulator using a gas discharge lamp and a mirror for forming a double image of the luminous plasma region of the lamp in a photocoagulation area adjusted for size by interchangeable field stops is improved for easier adjustability when field stop sizes are changed. A manually operable screw ring moves the lamp axially relative to the mirror to adjust the separation of one image from the other relative to the size of the field stop, and the side of the field stop facing toward the coagulation area is illuminated for brightening the environment of the coagulation area for easier observation.

What is claimed is: 
     
       1. A photocoagulator comprising (a) a gas discharge lamp elongated along a lamp axis and having a light output path along an optical axis approximately perpendicular to said lamp axis,   (b) optical means in said light output path for forming an image of light from said lamp at a distance along said optical axis from said lamp,   (c) a mirror arranged on said optical axis on the opposite side of said lamp from said optical means, for reflecting light from said lamp along said optical axis and through said optical means to form a second image at a distance,   (d) a plurality of interchangeable field stops,   (e) means for holding said field stops in position so that any selected one of said field stops may be brought to a position aligned with said optical axis at said distance from said lamp,   (f) manually operable means for moving said lamp axially along said lamp axis to adjust said first mentioned image relative to said second image and to the selected field stop aligned with said optical axis, and   (g) means for illuminating the side of the selected field stop which is remote from said lamp.   
     
     
       2. The photocoagulator of claim 1 wherein said mirror is arranged in a housing and said axial movement producing means includes a rotatable screw ring for moving said lamp relative to said housing. 
     
     
       3. The photocoagulator of claim 2 including a mark and a scale arranged on said housing and said screw ring for indicating the position of said lamp. 
     
     
       4. The photocoagulator of claim 1 including means for deriving light for said illuminating means from said lamp. 
     
     
       5. The photocoagulator of claim 4 including a light pipe arranged for receiving light from said lamp, and a reflecting element arranged for directing light from said light pipe onto said selected field stop. 
     
     
       6. The photocoagulator of claim 1 including an outer housing, an intermediate housing, and an inner housing, and wherein said mirror and said field stops are mounted in said outer housing, said intermediate housing is movable relative to said outer housing in the direction of the axial extent of said lamp, said lamp is mounted in said inner housing, and a universal joint means supports said inner housing in said intermediate housing for allowing said inner housing to tilt relative to said intermediate housing in two predetermined planes. 
     
     
       7. The photocoagulator of claim 6 wherein said universal joint means includes a portion of a sphere and a socket shaped to receive said sphere portion. 
     
     
       8. The photocoagulator of claim 6 including a pair of adjusting screws coupled between said inner housing and said intermediate housing for adjusting said tilt of said inner housing. 
     
     
       9. The photocoagulator of claim 6 wherein said axial movement producing means includes a rotatable screw ring between said outer housing and said intermediate housing. 
     
     
       10. The photocoagulator of claim 9 including a mark and a scale arranged on said housing and said screw ring for indicating the position of said lamp. 
     
     
       11. The photocoagulator of claim 10 including means for deriving light for said illuminating means from said lamp. 
     
     
       12. The photocoagulator of claim 11 including a light pipe arranged for receiving light from said lamp, and a reflecting element arranged for directing light from said light pipe onto said selected field stop. 
     
     
       13. The photocoagulator of claim 12 including a pair of adjusting screws coupled between said inner housing and said intermediate housing for adjusting said tilt of said inner housing. 
     
     
       14. The photocoagulator of claim 12 wherein said universal joint includes a portion of a sphere and a socket shaped to receive said sphere portion. 
     
     
       15. The photocoagulator of claim 6 including means for deriving light for said illuminating means from said lamp. 
     
     
       16. The photocoagulator of claim 15 including a light pipe arranged for receiving light from said lamp, and a reflecting element for directing light from said light pipe onto said selected field stop.